In modern medicine, there are increasing needs for more advanced medical (including surgical) instruments with higher and more flexible functionalities. While there has been progress in micro-surgery in recent years, the current or traditional medical instruments have not been able to meet the most demanding requirements. For example, certain complex surgeries require a high degree of accuracy, while the current surgery instruments fails to meet this demand for not only lacking sufficient precision or functionalities, but also heavily relying upon manual operations.
Further, there are needs for lower cost medical instruments to reduce overall health cost. In some cases, medical instruments can only be disposable (one-time use) due to technical requirements and practical considerations, which requires a high volume, cost effective manufacturing technology.
Currently, most medical instruments for micro-surgeries are mechanical devices with single functionality, e.g., for cutting tissues or stitching a wound. These conventional surgical instruments, especially those with cutting edge, are mostly made in mass of metals such as stainless steel or tungsten. They are generally ground from harder materials such as diamonds, silicon and sapphire. See, e.g., US 2005/0188548 A1. Although this method is economic for making surgical blades, it has some challenges. For instance, the blade edge's sharpness lacks consistency and sometimes even varies significantly. A mechanical sharpening process will result in imperfections on the blade edge and thus is generally not able to lead to a superior sharp blade edge or a micro-miniature surgical blade. Further, one cannot use the process to carve second-order cutting edge structures such as desired asperities, serrations and inside angles.
A relatively new method for manufacturing surgical blade employs more advanced techniques in processing the stainless steel than grinding, in which the blade is then electrochemically polished to achieve a sharp edge. This process has been found to produce blades with a more consistent sharpness in the blade edge. However, the chemical process will still lead to imperfections on the surface of the blade by the corrosion, and the sharpness consistency is still to be improved for high-precision surgeries. As a result of these minute imperfections, a conventional steel surgical blade cannot cut tissues without tearing some of them. Such tearing of tissues during a surgery may slow down healing of the wound and even result in formation of scar tissue during and after the healing process.
Recently, a microelectronic fabrication methodology has been proposed for a micro-miniature tip assembly. It is fabricated using photolithography and anisotropic etching. Specifically, the crystalline form of silicon is used as advantage by etching along the grain boundaries to form a pit in a silicon substrate. Tungsten is then deposited into the pit to form a sharp tip for use in a scanning tunneling microscope assembly. However, the angle of the tip edge is determined and limited by the crystalline orientation angle of the silicon itself. Even if the substrate is switched to sapphire or ruby, the angle is still a constant which is determined by the crystal orientation of the substrate material. See, e.g., U.S. Pat. No. 4,916,002.
There have been a few other proposals for the manufacturing of surgical blades using silicon. See, e.g., US 2005/0266680 A1, U.S. Pat. No. 5,619,889, U.S. Pat. No. 5,579,583, and U.S. Pat. No. 7,728,089. However, in one form or another, these relatively newer processes are limited due to their inability to manufacture blades in various configurations and at a disposable cost. Many of these proposals are based on anisotropic etching of silicon which is highly directional, with different etch rates in different directions. Although this process can produce a sharp cutting edge, due to its very nature, it is still limited in not being able to attain certain blade shapes and bevel angles. Wet bulk anisotropic etching processes, such as those employing potassium hydroxide or hydroxyl potassium (KOH), ethylene-diamine/pyrcatechol (EDP) and trimethyl-2-hydroxethylammonium hydroxide (TMAH) baths, etch along a particular crystalline plane to achieve a sharp edge. This plane, typically in silicon, is angled 54.7° from the surface plane in the silicon wafers. This creates a blade with an included bevel angle of 54.7°, which has been found to be clinically unacceptable in most surgical applications as being too obtuse. This application is even worse when this technique is applied to making double bevel blades, as the included bevel angle is 109.4°. The process is further limited to the blade profiles that it can produce. The etch planes are arranged 90° to each other in the wafer. Therefore, only blades with rectangular profiles can be produced.
Further, most of the prior proposed surgical instruments are mechanical devices and are used as knives, tweezers, saws, pins, clamps, and hooks. They are not suitable for integrating with other devices having, e.g., physical, optical, electrical, chemical, thermal or acoustic functions.
The present invention aims to provide solutions to the above-described problems and challenges.